Crystal and Molecular Structural Features of Indolin-2-One Derivatives with Sterically Hindered Phenol Moieties

The crystal and molecular structure of four indolin-2-ones with a bulky phenol substituent is studied by single crystal X-ray diffraction. All structures contain a sterically loaded 4-hydroxy-3,5-di-tert-butylbenzyl substituent at the N(1) position of the indole heterocycle. The crystal unit cells of two compounds with the thiosemicarbazone substituent at the C(3) atom of the cycle include one DMSO solvent molecule and the cells of two other molecules with the oxygen atom at the same position do not include solvent molecules. In two of the studied structures the thiosemicarbazone moiety has the Z,E,E configuration favorable for manifestation of the biological activity of these compounds. In three of four molecules the OH group of the bulky substituent at the N(1) atom of the cycle is not involved in hydrogen bonds due to steric hindrances.